Lubricating oils



United States Patent 3,310,491 LUBRICATING OILS Neville Murray Jones, Blackwood, and Robert James Stephenson, Cwmbran, England, assignors to Monsanto Chemicals Limited, London, England, a British company No Drawing. Filed Jan. 13, 1966, Ser. No. 520,363 Claims priority, application Great Britain, Jan. 14, 1965, 1,650/65; Mar. 11, 1965, 10,422/65 14 Claims. (Cl. 25246.6)

This invention relates to compositions comprising a combination of a phosphosulfurized terpene and an aralkyl phenol compound and to lubricating oil compositions containing a phosphosulfurized.terpene and an aralkyl phenol.

Phosphosulfurized terpenes have previously been pro posed as additives having beneficial effects on the propcuties of lubricating oils, including the effect of rendering the oil more resistant to oxidation. At the elevated temperatures at which a lubricating oil in a moderninternal combustion engine is required to function, however, the phosphosulfurized terpenes tend to have a somewhat adverse effect on the corrosion of bearings.

It has now been found that lubricating oil compositions containing a phosphosulfurized terpene and an aralkyl phenolic compound exhibit a synergistic eifect with respect to reducing bearing corrosion.

The present invention accordingly includes a lubricating oil composition comprising a mixture of a phosphosulfurized terpene and. an aralkyl phenol having the formula where R can be aralkyl or substituted aralkyl, R can be alkyl or substituted alkyl, n is a whole number having a value of from 1 to 5, m is a whole number having a value of from 0 to 4, provided that the sum of n+m is not greater than and provided that where Ris ortho to the phenolic hydroxyl group, R' is primary or secondary with respect to the bond between the aromatic phenolic ring and the alkyl radical.

An aralkyl phenol when used alone imparts a measure of oxidation resistance to lubricating oil, but like the phosphosulfurized terpenes, it may exhibit an adverse effect on bearing. corrosion at high temperatures. The effect we have now observed, whereby bearing corrosion is reduced significantly below the level which occurs when either the phosphosulfurized terpene or the aralkyl phenol is used alone is thus synergistic.

The invention also includes a concentrate of an antioxidant composition as defined above in a lubricating oil,

and a lubricating oil composition comprising a lubricating oil and a minor proportion of an antioxidant composition of this invention.

The phosphosulfurized terpene in the composition of this invention is preferably a phosphosulfurized dicyclic terpene, preferably one obtained by the phosphosulfurization of ot-pinene or a commercial terpene product containing a major proportion of a-pinene.

3,310,491 Patented Mar. 21 1967 Preferred aralkyl phenol compounds generally contain from 1 to 3 aralkyl groups and diaralkyl phenols, especially 2,4- and 2,6-diaralkyl phenols or mixtures of aralkyl phenols consisting predominantly of aralkyl phenols, are particularly effective. In addition, aralkyl phenols wherein in has a value of 0 or a value such that the total number of carbon atoms in the alkyl groups is not more than 3 are effective. Also, aralkyl phenols in which 111 has a value of one or more and there is at least one alkyl group R' which contains five or more carbon atoms are preferred aralkyl phenol compounds.

The phosphosulfurized terpenes that have been proposed as lubricating oil additives are generally the reac tion products of a phosphorus sulfide with a terpene hydrocarbon having the formula C H or more usually with isomeric mixtures of such compounds. Commercial terpene products from which the phosphosulfurized materials can be derived may also contain small amounts of, for instance, terpene alcohols, 'sesquiterpenes and diterpenes. Many terpene hydrocarbons having the above formula are known, including monocy-clic terpenes such as dipentene, and bicyclic terpenes. As indicated above, the preferred phosphosulfurized terpenes for use in the present invention are those derived from the latter class of terpenes. In addition to the preferred a-pinene, this class includes such materials as a-pinene, camphene, fenchene, bornylene, thujene and sabinene. The commercial grades of turpentine, most of which contain 85% or more of a-pinene, are often suitable starting materials from which the preferred phosphosulfurized terpenes can be obtained.

The phosphosulfurization of the terpene is normally carried out by heating the terpene with a phosphorus sulfide at an elevated temperature, for example a temperature in the range of -l8-0 C., optionally in the presence of an inert diluent, which can conveniently be a lubricating oil. The preferred phosphorus sulfide is phosphorus pentasulfide, although other sulfides or mixtures of phosphorus sulfides and sulfur, can be employed.

Particularly effective antioxidants for use in the compositions of this invention are obtained by the reaction of one molar proportion of phosphorus pentasulfide with from 3 to 5 molar proportions, and especially with from 3.8 to 4.2 molar proportions of the terpene.

The aromatic portion of an aralkyl group in an aralkyl phenol useful according to the present invention is generally an aryl group, for instance a phenyl or a substituted aralkyl group, for example, a halogen-substituted aryl group or an alkyl substituted aryl group. Preferably the number of carbon atoms in the alkyl portion of the aralkyl group does not exceed four, and the aralkyl substituent' can thus be for example a benzyl, phenylethyl, tolylethyl or phenylpropyl group. The alkyl portion of the aralkyl radical can have a straight chain of carbon atoms or a branched chain of carbon atoms. In addition, aralkyl phenols where at least one aralkyl group is attached to the phenol nucleus by a secondary carbon atom as, for example, in an a-methylbenzyl or oz-ethylbenzyl group, are particularly effective.

A further preferred feature of the aralkyl phenol is that at least one aralkyl group should be present in an ortho position to the phenolic hydroxyl group.

The aralkyl phenols in which m in the above formula of the aralkyl phenols has the value 0 or a value such that the total num-ber of carbon atoms in the alkyl group or groups R is not more than three, are aralkyl derivatives of. phenol itself and of alkylphenols such as for instance the oresols, xylenols, ethylphenols and isopropylphenols.

In an aralkyl phenol containing one or more nuclear alkyl groups R at least one of which contains five or more carbon atoms, the other alkyl group or groups may themselves each contain four or more carbon *atoms or less than four carbon atoms.

In the more accessible alkyl-substituted aralkyl phenols the alkyl group or groups occupy one or more of positions 2, 4 and 6, although aralkyl phenols having an alkyl substituent in the 3- or 5-position can be used. Generally either one or two alkyl groups are present, and a preferred class of aralkyl phenols, in respect of the alkyl substituents, are those containing a single alkyl group of five or more carbon atoms in the para position to the phenolic hydroxyl group or one such group together with a methyl or ethyl group.

A further preferred feature of such alkyl-substituted aralkyl phenols is the presence of an alkyl group containing 5 or more carbon atoms, which confers on the aralkyl phenol increased compatibility with the oil in which it is used. The alkyl group can contain for example from 5 to 24 carbon atoms, and can be arranged in a straight or branched chain. Examples of such alkyl groups are amyl, hexyl, octyl, nonyl, dodecyl, tridecyl, tetradecyl, pentadecyl and octadecyl groups. In practice, the alkyl group is often one derived from an alkylate fraction, for example an octyl group corresponding to diisobutylene, a nonyl group corresponding to propylene trimer, or a dodecyl group corresponding to propylene, tetramer or triisobutylene. Such alkylate fractions are in some instances mixtures of olefins, and where this is so the derivative aralkyl phenols are correspondingly mixtures of a number of individual compounds. Such mixtures are, however, fully comparable in performance with the pure aralkyl phenols while having economic advantages over the latter.

Specific examples of aralkyl phenols useful according to the present invention are:

. 2,6-bis oc-o-dimethylbenzyl) -4( 1' 1 ,3',3 -tetramethylbutyl) phenol; 2,6-bis(a,a-dimethylbenzyl)-4(4',6-dinrethylhept-2'-y l) phenol; 2,6-bis (ct-methylbenzyl) -3-methyl-4-(4',6'-dimethylhept- 2'-yl) phenol; 2,6-bis u,oz-dimethylbenzyl) -4 4,6'-dimethylhept-2-yl) phenol; 2,6-bis(a-methylbenzyl) 4 dodecylphenyl, the dodecyl group being one derived from propylene tetramer; 2,6-bis u-methylbenzyl) -4-cetylphenol; 2,4-bis(ot-methylbenzyl) -3-n-pentadecylphenol, and 2,6-bis(a-rnethylbenzyl)-4-n-octadecylphenol.

Lubricating oils which can be used as the base oils to which the aralkyl phenol and phosphosulfurized terpene compounds of this invention are added are not limited as far as the synergistic eifects are concerned and accordingly can be lubricating oils which are of a naphthenic, paraflinic or other hydrocarbon base as well as lubricating oils derived from coal products, and synthetic oils, such as alkylene polymers, alkylene oxide polymers, dicarboxylic acid esters, alkylated benzene, silicate esters, silicon polymers and the like are suitable.

The phosphosulfurized terpene and the aralkyl phenol are normally each present in the lubricating oil compositions of the invention in amounts Varying from 0.05 to 10% of the total weight of the composition, preferably from 0.1 to 5% or in a ratio respectively of 200:1 to 1:200, the total amount of both additives present in the lubricating oil being from 0.10 to 20% by weight of the total composition.

The concentrates and antioxidant compositions of the invention are of course intended for addition to lubricating oils, and the relative proportions of the antioxidants in these mixtures are therefore selected according to the proportions required in the lubricating oil composition.

The proportion of oil in the concentrates of the invention can vary from, for example, 10% to or from 20% to 80% of the total weight of the concentrate.

The antioxidant compositions, concentrates and lubricating oil compositions of the present invention can 0ptionally contain other additives having beneficial effects on the properties of the oil. Such additives include for instance materials having detergent properties, for example, oil-soluble alkaline earth metal derivatives of phosphosulfurized polyolefines, alkali or alkaline earth metal salts of petroleum or alkylbenzene sulfonates, or amine salts of olefin/maleic anhydride copolymers, antiwear additives, for example aryl phosphates such as for instance tricresyl phosphate, viscosity improvers and pourpoint depressants.

The invention is illustrated by the following non-limiting examples.

' Example I A series of concentrates containing a range of proportions of a phosphosulfurized terpene and an aralkyl phenol in mineral oil was prepared. The amount of oil varied from 14.5 to 36.5% by weight of the concentrates.

The phosphosulfurized terpene was obtained by heating at approximately C. a mixture of one molar proportion of phosphorus pentasulfide and four molar proportions of a-pinene in the presence of a mineral oil as diluent. The aralkylated phenol was obtained by the reaction of approximately 2 molar proportions of styrene With one molar proportion of phenol in the presence of an acid catalyst, and contained a mixture of 2,4- and 2,6-bis(ot-methylbenzyl) phenols with some monoand tris(a-methylbenzyl) phenols.

An appropriate amount of each concentrate was then added to a separate portion of a base stock having the following composition:

Parts by wt. Mixed detergent containing barium and calcium sulfonates with a polymeric ashless dispersant 6.5 Phosphate ester 0.2 Mineral oil of viscosity 11 centistokes at 210 F. Bal.

to give the percentages of the phosphosulfurized terpene and aralkylphenol shown in Table I.

Each lubricating oil composition was then evaluated using the Petter W1 test procedure, bearing weight loss being determined after a period of 36 hours. Some formulations associated With low bearing loss in addition were subjected to test for a further 36 hour period. The results obtained are shown in Table I.

TABLE;

Bearing Bearing Run Antioxidant and percent by weight of weight loss weight loss N o. lubricating oil compositions (rngs) after (mgs) after p 36 hours 72 hours Phosphosulfurized terpene, 0.56 19 Aralkyl phenol, 1.0, 0.2a. g; Phosphosulfurized terpene, 0.5.- Aralkyl phenol, 0.2 Phosphosulfurized terpene, 0.4 Aralkyl phenol, 0.25 Phosphosulturized terpene, 0.28-

Aralkyl phenol, 0.5 Phosphosulfurized terpene, 0.28. Aralkyl phenol, 0.75 Phosphosuliurized terpene, 0.4 Aralkyl phenol, 0.75

Example 2 one lubricating oil composition containing 0.25% by weight of product A and 0.4% by weight of the phosphosulfurized terpene (Composition 1), and a second lubricating oil composition containing 0.25% by weight of product B and 0.4% by weight of the phosphosulfurized terpene (Composition 2).

The compositions were tested by the Pet'ter Wl'procedure and gave the following results which are listed in Table II.

TABLE II Bearing Weight Run No. Loss (rugs) after 36 hours 8 Composition 1 4 9 Composition 2 8 Example 3 Mineral oil concentrates were prepared containing different proportions of the phosphosulfurized terpene de scribed in Example 1 and an aralkyl phenol-obtained by the reaction of 2 molar proportions of styrene with one I molar proportion of 4-nonylphenol and consisting essentially of 2,6-bis(a-methylbenzyl)-4-nonylphenol.

An appropriate amount of each concentrate was then added to a separate portion of the base oil stock described in Example 1 to give the percentages of the phosphosulfurized terpene and aralkyl phenol shown in the table below. Each lubricating oil composition was then evaluated using the Petter W1 test procedure, the following results being obtained which are listed in Table III.

Tables I, II and III effectively demonstrate the reduction in corrosion rates which are obtained with lubricating oil compositions containing the additive combinaton of an aralkyl phenol compound and a phosphosulfurized terpene. The bearing corrosion rates obtained by the use of either additive alone have been found to be significantly higher than the combination of the two additives. In particular, runs Nos. 1 and 2 in Table I demonstrate the higher bearing weight loss after only 36 hours with the individual additives, whereas runs Nos. 4, 5, 6 and 7 demonstratethat the combination of the two additives show bearing losses which are extremely small and practically zero. The previous examples demonstrate the synergism which is obtained by the use of the two additives which cannot be obtained by the use of the additives singly.

While this invention has been described with respect to various specific examples and embodiments, it is understood that the invention is not limited thereto and that ,it can be variously practiced within the scope of the following claims.

What is claimed is:

1. A composition comprising (A) a phosphosulfurized tenpene and (B) an aralkyl phenol represented by the structure wherein R is selectedjfrom the group consisting of aralkyl and substituted aralkyl, R is selected from the group consisting of alkyl and substituted alkyl, n is a whole number having a value from 1 to 5, m is a whole number having a value from 0 to 4, provided that the sum of n-l-m is from 1 to 5 and provided that when R is ortho to the phenolic hydroxyl group that R is selected from the group consisting of primary and secondary alkyl and primary and secondary substituted alkyl, the ratio of (A) to (B) being from 200:1 to 1:200.

2 A composition of claim 1 wherein the phosphosulfurized terpene is a phosphosulfurized dicyclic terpene.

3. A composition of claim 2 wherein the phosphosulfurized dicyclic terpene is a-pinene.

4. A composition of claim 1 wherein R is aralkyl and n is from 1 to 3.

5. A composition of claim 1 wherein R is a-methylbenzyl.

6. A composition of claim 1 wherein R is aralkyl and n has a value from 1 to 3 provided that at least one aralkyl group is present in a position ortho to the phenolic hydroxyl group.

7. A composition of claim 1 wherein m has a value of O to 3 provided that when m has a value from 1 to 3 the total number of carbon atoms in R and n (R) is from 1 to 3.

8. A composition of claim 1 wherein R contains from 1 to 24 carton atoms, n has a value of from 1 to 3 provided that at least one R contains from 5 to 24 carbon atoms.

9. A composition of claim 1 wherein n has a value of from 1 to 2, R is aralkyl, R is alkyl provided that R is present in a position ortho to the phenolic hydroxyl group and R is para to the phenolic hydroxyl group;

10. A composition of claim 9 wherein R contains from 5 to 24 carbon atoms.

11. A composition of claim 10 wherein R is nonyl.

12. A composition comprising a major amount of a lubricating oil and from 0.10% to 20% weight percent of a composition of claim 1.

8 13. A composition comprising a major amount of a lubricating oil and from 0.10% to 20% weight percent of a composition of claim 4.

14. A composition comprising a major amount of a 5 lubricating oil and from 0.10% to 20% weight percent of a composition of claim 11.

No references cited.

DANIEL E. WY MAN, Primary Examiner.

10 L. G. XIARHOS, Assistant Examiner. 

1. A COMPOSITION COMPRISING (A) A PHOSPHOSULFURIZED TERPENE AND (B) AND ARALKYL PHENOL REPRESENTED BY THE STRUCTURE
 12. A COMPOSITION COMPRISING A MAJOR AMOUNT OF A LUBRICATING OIL AND FROM 0.10% TO 20% WEIGHT PERCENT OF A COMPOSITION OF CLAIM
 1. 